Having the same problem and I'm on PS4.

I contacted Optus earlier and they told me to do a speed test which appeared to be fine, and there were no issues with NBN either. They just told me that it seems to be a game problem.

Tethering to mobile hotspot is fine tho. Hitting the dummy seems fine as well, but the moment I enter an instance, party members start teleporting here, there and my casts start clipping bad.